46 



MR, L. A. BORRADAILE OX THE 



(text-fig, 1), the arrangement of the parts is strikingly suggestive 

 of those of the phyllopod limb, the so-called "dorsal cirrus" — 

 really the notopodium, whose small size and position upon the 

 base of the large straight neuropodium make the parapodium. 

 uniramous — standing for the flabellum, the gill for the epipodite, 

 and the short, broad, ventral cirrus for the gnathobase. Needless 

 to say, no more than analogy can be claimed for this likeness. 

 The point of origin of the Arthropoda from their worm-like 

 ancestors is not to be settled merely by a general and hypothetical 

 i-esemblance of the limbs. 



Text-figure 19. 



Maxilla of Li/siosqiiilla maculala. 

 For lettering- see p. 71. 



6. It has already been pointed out (p. 39) that the presence 

 upon the hinder part of the head of Malacostraca, Ostracoda, and 

 Copepoda of appendages not greatly modified from the assumed 

 primitive type (text-figs. 13-21) justifies the surmise that in the 

 original crustacean the series of similar limbs extended further 

 forward than in Branchiopoda. Probably it resembled that of 

 the Trilobita in including all the appendages behind the anten- 

 nules, but comparison of the maxilla of the Decapoda wi^h the 

 pygidial limbs of Triarthrus sviggests that there was less unlike- 

 ness between the extreme members than in that genus. Each 

 appendage was no doubt capable of being used for swimming, for 



